/*
 * Copyright (C) 2017, hapjs.org. All rights reserved.
 */

"use strict";

var Base64 = {},
    decoder;

Base64.decode = function (a) {
    var i;
    if (decoder === undefined) {
        var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
            ignore = "= \f\n\r\t\xA0\u2028\u2029";
        decoder = [];
        for (i = 0; i < 64; ++i) {
            decoder[b64.charAt(i)] = i;
        }for (i = 0; i < ignore.length; ++i) {
            decoder[ignore.charAt(i)] = -1;
        }
    }
    var out = [];
    var bits = 0,
        char_count = 0;
    for (i = 0; i < a.length; ++i) {
        var c = a.charAt(i);
        if (c == '=') break;
        c = decoder[c];
        if (c == -1) continue;
        if (c === undefined) throw 'Illegal character at offset ' + i;
        bits |= c;
        if (++char_count >= 4) {
            out[out.length] = bits >> 16;
            out[out.length] = bits >> 8 & 0xFF;
            out[out.length] = bits & 0xFF;
            bits = 0;
            char_count = 0;
        } else {
            bits <<= 6;
        }
    }
    switch (char_count) {
        case 1:
            throw "Base64 encoding incomplete: at least 2 bits missing";
        case 2:
            out[out.length] = bits >> 10;
            break;
        case 3:
            out[out.length] = bits >> 16;
            out[out.length] = bits >> 8 & 0xFF;
            break;
    }
    return out;
};

Base64.re = /-----BEGIN [^-]+-----([A-Za-z0-9+\/=\s]+)-----END [^-]+-----|begin-base64[^\n]+\n([A-Za-z0-9+\/=\s]+)====/;
Base64.unarmor = function (a) {
    var m = Base64.re.exec(a);
    if (m) {
        if (m[1]) a = m[1];else if (m[2]) a = m[2];else throw "RegExp out of sync";
    }
    return Base64.decode(a);
};

module.exports = Base64;